1. Field of the Invention
This invention relates to marine cargo vessels and more particularly to a system for selective pressurization of an expandable hollow gasket interposed between a hatchway defining an opening within the deck for access to a cargo storage compartment within the vessel interior and a hatch cover interfittingly mounted on the hatchway and closing off the opening.
2. Description Of The Prior Art
Marine vessels such as cargo ships and the like store massive amounts of cargo within the marine vessel hull in cargo compartments normally separated by laterally directed, longitudinally spaced bulkheads. Access to the cargo storage compartments is normally achieved through hatchways forming circular or rectangular openings within the deck of the vessel, these hatchway openings normally being covered by removable hatch covers of corresponding configuration having a projecting portion which fits within the hatchway opening.
Conventionally, the periphery of the hatch cover is extended beyond the hatchway opening, and the hatch cover may be hinged to the hatchway member or simply held in place by gravity force.
Conventional hatch covers are somewhat loosely maintained on the hatchway member and as a result during adverse weather, with waves crashing over the deck, sea water seeps between the hatch cover and the hatchway member and into the cargo compartment.
The applicant, in U.S. Pat. No. 3,897,743 entitled "Multi-hull Convertible Cargo Carrier Submarine" issuing Aug. 5, 1975, discloses an arrangement for sealing and locking of a plurality of hatches to a marine cargo hull (of a submersible type) in which the portion of the hull forming the hatchway or hull opening carries, in this case, hinged hatches or hatch covers. Around the complete edge thereof, a seal and locking groove is provided, characterized by a cross section whose entry portion is of a smaller width than the portion of the groove internally thereof. Further provided about the periphery of the hinged hatch cover, on its lower face, is an expandable hollow sealing and locking gasket. By subjecting the gasket to compressed air or hydraulic liquid under pressure, the gasket expands to fill the groove and to effect both a lock and a waterproof seal for the hatch cover.
It is an object of the present invention to provide an improvement in such a combined lock and sealing mechanism in terms of a control system for controlling the pressurization and thereby the initiation and termination of the lock and seal for the hatch cover and for either initiating or increasing the fluid pressure application to the deformable, expandable gasket in response to the hatch cover wave impact during adverse weather and rough seas.
It is a further object of the present invention to provide an improved combined hatch cover locking and sealing mechanism of this type which may be incorporated within an existing marine vessel by simple modification of the hatch cover and hatchway defining the deck opening for receiving the hatch cover.